Power transmission

ABSTRACT

A remote control system for ship&#39;&#39;s rudders includes a hydraulic rudder actuator and a reversible variable displacement pump connected to drive it, the pump displacement being under the control of a hydraulic bridge circuit utilizing a pair of bleed circuits controlled respectively by variable command orifices and variable response orifices. The command orifices are constituted by a pair of summing valves responsive to the algebraic sum (or difference) of the angular displacements of a command actuator on the one hand and the rudder actuator on the other hand. The command actuator is hydraulically driven and electrically controlled by a closed loop servo system including a helm control which may comprise an automatic pilot.

United States Patent [191 Jeffery et al.

1451 Mar. 26, 1974 POWER TRANSMISSION [75] Inventors: Robert W. Jeffery, Franklin; Robert H. Breeden, Metamora, both of Mich.

[73] Assignee: Sperry Rand Corporation, Troy,

Mich.

[22] Filed: Jan. 17, 1972 21 Appl. No.: 218,183

Kumpf et al.... 60/52 S Kutzler 244/78 3,527,186 9/1970 Wennberg et al 114/144 R Primary Examiner-Duane A. Reger Assistant ExaminerBarry L. Kelmachter Attorney, Agent, or Firm--Theodore Van Meter 5 7] ABSTRACT A remote control system for ships rudders includes a hydraulic rudder actuator and a reversible variable displacement pump connected to drive it, the pump displacement being under the control of a hydraulic bridge circuit utilizing a pair of bleed circuits controlled respectively by variable command orifices and variable response orifices. The command orifices are constituted by a pair of summing valves responsive to the algebraic sum (or difference) of the angular displacements of a command actuator on the one hand and the rudder actuator on the other hand. The command actuator is hydraulically driven and electrically controlled by a closed loop servo system including a helm control which may comprise an automatic pilot.

5 Claims, 7 Drawing Figures PMENTEI) R25 974 SHEET 3 0F 4 POWER TRANSMISSION Subject matter such as that disclosed by FIGS. 3 to 6 hereof is claimed in a divisional application, Ser. No. 350,664 filed Apr. 12, 1973.

The steering arrangements for large ships require large forces at the rudder post and the ability to control them from the remotely located ships bridge. This requirement was commonly met in the past by the use of a large hydraulic actuator for the rudder, a reversible variable displacement pump to drive the actuator and a follow-up control system from the helm at the bridge to the pump. The follow-up system requires large and expensive differential gearing as well as cumbersome arrangements for transmitting mechanical motion from the bridge to the rudder drive. In the effort to reduce the cost and complication of such systems, follow-up controls have been utilized in which the rudder actuator is controlled by a mere three-position directional valve, sometimes referred to as a bang-bang system. Such a system requires only a simple electrical connection from the helm to the rudder drive, but has several drawbacks, among them being the lack of precision in determining rudder position, the imposition of shock loads and low durability.

The present invention aims to provide an improved ships rudder control system which provides reliable follow-up action at lower cost than previous follow-up systems, which permits the use of simple electric wiring between the bridge and the rudder drive and which avoids imposing shock loads on the system.

The invention accomplishes this by the provision of a ships rudder control system which comprises a hydraulic rudder motor and a reversible variable displacement pump for shifting the motor, means for controlling the pump displacement including a servomotor and a hydraulic bridge having a pair of bleed circuits carrying a continuous small flow of pilot control fluid, command means for varying the resistance in a first portion or portions of the bleed circuits, and response means for varying the resistance in a second portion or portions of the bleed circuits as the pump displacement changes, said command means including a first member movable at command and a second member movable in follow-up motion responsive to shifting of the rudder motor.

IN THE DRAWINGS:

FIG. 1 is a hydraulic circuit diagram ofa rudder control system incorporating a preferred form of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a portion of FIG. 1 ingreater detail.

FIG. 3 is a longitudinal cross section of a command actuator incorporated in the system of FIG. 1.

FIG. 4 is a cross section on line 4-4 of FIG. 3.

FIG. 5 is a cross section on line 5-5 of FIG. 3.

FIG. 6 is a cross section on line 6--6 of FIG. 3.

FIG. 7 is a fragmentary detail ofa portion of the control mechanism.

Referring now to FIG. 1, there is indicated an oscillating paddle motor 10 secured to a rudder post 12 and supplied by hydraulic manifolds 14 and 16. Connected across the latter are a pair of over-load relief valves 18 and a bypass valve 20. The three lobed rotor 22 has an arm 24 connected to a response link 26 for the purpose of repeating the motion of the rudder motor 10 at a point in the control mechanism. In FIG. 1, there is shown a duplicate set of power and control devices for alternate stand-by use and only one of them will be described.

The manifolds 14 and 16 are supplied through main power lines 28 and 30 and a solenoid operated blocking valve 32 (for manually locking the rudder post) from a reversible variable displacement pump 34 driven by an electric motor 36. A pilot control fluid pump 38 is also driven by the motor 36 and supplies fluid to a solenoid operated command valve 40 through a line 42. A branch 44 supplies pilot control fluid to the displacement regulating mechanism of the pump 34 which is illustrated in more detail in FIG. 2 and which will be described later.

The displacement regulating system is under the control ofa summing valve 45, the body 46 of which is connected to link 26 by a pin and slot connection 48. The inner rotor 53 of the valve 45 is oscillated by a command actuator 50 having a piston 52 mechanically connected to the rotor 53. This connection is indicated in FIG. 1 as a link 54, but may be any other suitable connection such as will be later described in connection with FIGS. 3, 4, 5 and 6. The supply conduits 56 and 58 between command valve 40 and command actuator 50 may include suitable adjustable restrictions 60 and 62 with associated check valves for the purpose of regulating the speed of motion of the piston 52. The command actuator 50 also operates a synchromotor 64 for generating a feedback signal derived from the position of the piston 52.

Referring now to FIG. 2, the pump displacement regulating mechanism utilizes a servomotor comprising small area piston 66 subjected to constant pilot control pressure through branch line 68 and a large area piston 70 under the control of three-way directional valve 72 which is supplied with pressure through branch line 74. Pump 38 also supplies charging fluid to the pump 34 through priority valve 76 and branch line 78 leading to the usual checkvalves 80 connected to the main power lines 28 and 30. A control pressure relief valve 82 limits the charging pressure while a shuttle valve 84 and higher pressure relief valve 86 serve as secondary protection for the main power lines 28 and 30. Primary protection for them is provided by checkvalves 88 and pilot operated relief valve 90-92.

The parts thus far described may be located in the steering engine room adjacent the rudder post and command control over them may be exercised from the ships bridge through electric lines alone. Thus, referring to FIG. 1, a helm device 94, which may be an automatic pilot or a manual helm switching device, may be connected by lines 96-98 to control the command valve 40. One line supplies a port rudder signal of uniform magnitude while the other supplies a similar starboard rudder signal. It will be understood that although a single line is illustrated, these each represent the usual two wire connection. The command actuator position as received at the synchromotor 64 is transmitted as an electrical signal through lines 100 to the bridge, where it may serve to supply either an autopilot or a rudder position repeater in the usual manner.

In FIGS. 3, 4, 5 and 6, there is illustrated a preferred construction for the command actuator 50, its piston 52 and linkage 54 as well as the summing valve 45. The body 46 of the summing valve 45 has a tubular stem 102 rotatable in a bore 104 of the body 50 and has secured to it at its outer end an arm 106 (see FIG. 7). The outer end of arm 106 is connected by link 108 to the pin 48 and link 26 coming from the rotor of the main rudder motor. The summing valve rotor 53 is formed at the lower end of an oscillating shaft 110 mounted in the bore of the sleeve 102 and in a bore 112 in the body 50.

The summing valve 45 provides a pair of variable resistances, one for each of two bleed circuits 114 and 116 (see FIG. 2) which form part of a hydraulic bridge controlling the valve 72. The rotor 53 is formed with a pair of arcuate grooves 118 leading to the lower end of the stem 110 in FIG. 3, and connected to reservoir through the central passage 120. Each of the variable resistances is comprised of a pair of dimetrically opposite ports 122 and 124 respectively, these ports being connected together by drilled passages 126 and 128 respectively. The bleed circuits 114 and 116 connect to the ports 122 and 124 respectivelyby flexible hoses. At its upper end, the shaft 110 is connected to the rotor 130 of synchromotor 64, the body of which is mounted by a bracket 132 to the body 50.

The stem 110 which constitutes the rotor 53 of the summing valve is arranged to be connected for oscillatory movement by a radial arm 54 in FIG. 3 which extends through a bore in a trunnion pin 134 carried by the piston 52. Thus, longitudinal movement of the piston 52 (FIG. 4) will produce oscillatory movement of the stem 110. Accordingly, the resistance at ports 122 and 124 may be varied equally and oppositely as the stem 110 moves away from its center position in one direction or the other. This reciprocally changes the resistance in the bleed circuits 114 and 116 and because of the hydraulic bridge circuit charateristics, causes the valve 72 to shift to one direction or the other and energize or deenergize the large area servomotor 70.

A similar pair of variable resistances are contained in a response valve 136 (FIG. 2) which receive pilot control fluid through a branch 138 and distributes it to the two bleed circuits 114 and 116 at rates which depend upon the position of the stroke regulating mechanism of the pump 34. The hydraulic bridge control circuit may be similar to that illustrated in the copending application of Robert H. Breeden, Ser. No. 182,677, now U.S. Pat. No. 3,758,235 filed Sept. 22, 1971 for Power Transmission.

The operation of the present ships rudder control system starting with the electric and the hydraulic circuits suitably activated and with the system in a stable state, wille understood if it is assumed that the-helm control 94 is adjusted either automatically, if it is an auto-pilot, or manually, if it is a manual helm, so as to energize, for example, the line 96 calling for a port rudder motion. This shifts the command valve 40 to supply pilot control fluid, say to the line 58 and the right end of command actuator 50, causing piston 52 to move toward the left in FIG. 1'. The longer this signal is applied, the farther piston 52 will move. This motion is repeated back to the bridge by synchromotor 64 and lines 100.

At the first incremental movement of piston 52, rotor 53 of the summing valve is shifted, thus upsetting the balance in the hydraulic bridge bleed circuits 114 and 116 causing valve 72 to shift to either energize or deenergize the large area servomotor 70 which will place the pump 34 on stroke in the appropriate direction to supply fluid to rudder motor 10. As the rotor 22 and the rudder post 12 move, that motion is transmitted by link 26 to the body 46 of the summing valve 45, (see FIG. 1) tending to wipe out the signal as represented in the hydraulic bridge. That is, the body 46 will follow up" the initial motion imparted to the rotor 53. When the command actuator piston 52 comes to rest in a new position, the rudder motion 22 will move the post 12 to its new position and that motion will have restored the ports in the summing valve to neutral, which restores valve 72 to neutral and cuts off further energization of the servomotor 70. Thus, the parts will be restored to their stable condition again with the rudder taking up a new position corresponding to the new position dictated at the helm 94.

The maximum throw of the rudder motor 10 may be regulated by limiting the stroke of the command actuator piston 52. For this purpose, the piston 52 may be provided with pins 140 on its ends which engage with adjustable poppet valves 142 mounted in the ends of the body 50. These poppet valves are in the fluid inlet and outlet passages 144 and, when seated, serve to block further ingress of fluid to their respective ends of the cylinder. By raising or lowering the body of the poppet valve 142, it is possible to vary the point at which the pin 140 allows the poppet to seat and thus limits the stroke of the piston 52.

We claim:

1. A ships rudder control system comprising a hydraulic rudder motor and a reversible variable displacement pump for shifting the motor, means for controlling the pump displacement including a servomotor and a hydraulic bridge having a pair of bleed circuits carrying a continuous small flow of pilot control fluid, command means for varying the resistance in a first portion of the bleed circuits, response means for varying the resistance in a second portion of the bleed circuits as the pump displacement changes, said command means including a first member movable at command and a sec- 0nd member movable in follow-up motion responsive to shifting of the rudder motor.

2. A system as defined in claim 1 which includes a hy-' draulic actuator for the command means and a closed loop servo system connected to drive the actuator in response to helm input.

3. A system as defined in claim 2 in which the servo system includes an electrically operated directional valve hydraulically connected to control the actuator and a remotely positioned helm electrically connected to the directional valve.

4. A system as defined in claim 3 including a position responsive electrical feed-back device driven by the actuator and electrically connected to the helm.

5. A system as defined in claim 4 having a common source of pilot control fluid for the pump servomotor,

the bleed circuits, and the actuator.

* m n a: 

1. A ship''s rudder control system comprising a hydraulic rudder motor and a reversible variable displacement pump for shifting the motor, means for controlling the pump displacement including a servomotor and a hydraulic bridge having a pair of bleed circuits carrying a continuous small flow of pilot control fluid, command means for varying the resistance in a first portion of the bleed circuits, response means for varying the resistance in a second portion of the bleed circuits as the pump displacement changes, said command means including a first member movable at command and a second member movable in follow-up motion responsive to shifting of the rudder motor.
 2. A system as defined in claim 1 which includes a hydraulic actuator for the command means and a closed loop servo system connected to drive the actuator in response to helm input.
 3. A system as defined in claim 2 in which the servo system includes an electrically operated directional valve hydraulically connected to control the actuator and a remotely positioned helm electrically connected to the directional valve.
 4. A system as defined in claim 3 including a position responsive electrical feed-back device driven by the actuator and electrically connected to the helm.
 5. A system as defined in claim 4 having a common source of pilot control fluid for the pump servomotor, the bleed circuits, and the actuator. 